Yes, I think people are private about it when they hold some spiritual beliefs but they are pretty vocal when they think it's all a load of hogwash.
I don't speak of my beliefs or practice at work but a colleague who is Chan Buddhist knows (I once did a retreat at the temple he goes to) and has told some others I think.
I guess generally among scientists and mathematicians, the credo is inquire into everything and accept the simplest explanation (as everybody knows). Theism requires a quarantine from this approach it seems and scientists who hold theistic beliefs seem to separate them from the way they approach just about everything else.
PS Cloaka! And there I was thinking what I do is useless...
PPS The evil chemistry teacher, eh? (just read the synopsis) I was a big time chemistry nerd at school and I could see myself ending up an explosives guru for some green or anti-capitalist terrorist group, but these have gone out of fashion it seems!